Warheads with shaped-charge munitions, also known as hollow charge munition, are known to pierce armors and thereby destroy the protected object from within and, its contents. This capacity of a shaped-charge results from the fact that upon detonation there forms an energy-rich jet also known as “thorn” or “spike” which advances at very high speed of several thousands of meters per second and is thereby capable of piercing even relatively thick armor walls.
Several arrangements have become available in recent years to afford protection against the penetrating effect of an exploding shaped charge, wherein a structure holding at least one reactive armor element, wherein reactive armor element comprises an array of layers comprising one or more plate layers and at least one layer of explosive or any other energetic material (‘energetic material’—a material releasing energy during activation/excitement), tightly bearing against at least one of the plate layers. The plate layers are made, for example, of metal or a composite material.
A basic reactive armor element comprises two metal plates sandwiching between them the layer of energetic material. Such prior art reactive armor elements are based on the mass and energy consuming effects of moving plates and their functioning is conditional on the existence of an acute angle between the jet of an oncoming hollow charge threat and the armor itself.
In general, a reactive armor element is a multi-layer body in which each layer tightly bears against each contiguous layer, wherein the multi-layer body includes an outer cover plate, at least one layer of energetic material, at least one intermediary inert body juxtaposed to each of the at least one energetic material layer. Upon activation/excitement of the energetic material (e.g. upon striking by shaped-charge warhead) the jet energizes the armor, where a vast energy discharge occurs so that within microseconds the discharged gases accelerate the metal plates and displaces them away from one another thus disrupting/defeating the jet, thereby loosing its energy to penetrate the protected enclosure.
Whilst efficiency and survivability of the armor are important, the overall performance of an armor is determined by comparing its efficiency versus its survivability. One criteria of an armor, having significant importance, is the ratio of weight per area unit of the armor element. Another criterion of importance is sensitivity of the energetic material. Whilst sensitivity may be an advantage for improving efficiency of the armor, it may reduce survivability of the armor and it may be problematic as far as complying with various transportation requirements.
There are known four principal groups of intermediate materials for armors, disclosed hereinafter in order of their energetic characteristic:
A. Explosive Reactive Armor (ERA):
Explosive Reactive Armor is the most effective technology to defeat hollow charges, kinetic projectiles, small arms, shrapnel etc. Advanced ERA concepts are considered leap-ahead technology against emerging anti-armor threats. The major challenges of applying ERA to ground combat vehicles are the use of an explosive material as an intermediate layer of the sandwich element, reducing survivability of the armor.
B. Self-Limiting Explosive Reactive Armor (SLERA):
Self-Limiting ERA provides reasonable performance, substantially better than NERA (see below), though less than ERA, with reduced effects on vehicle structures, as compared to ERA. The energetic material layer in SLERA has the potential of being classified as a passive material (NATO specification). SLERA can provide good multiple-hit capability in modular configuration. Thus, while the energetic material used in SLERA is not as effective as fully detonable explosives, this type of reactive armor may provide a more practical option than ERA owing to its survivability characteristics.
C. Non-Explosive Reactive Armor (NxRA):
Non-Explosive Reactive Armor provides a comparable efficiency to SLERA, comparable survivability to NERA (see below), and excellent multiple-hit capability against hollow charge warheads. NxRA's advantages over other reactive armor technologies are that it is totally passive and has substantially better efficiency than NERA. Energetic materials for NxRA are disclosed for example in DE 3132008C1 and in U.S. Pat. No. 4,881,448.
D. Non-Energetic Reactive Armor (NERA):
Non-Energetic Reactive Armor has limited efficiency against hollow charges. NERA's advantage is that it is totally passive and thus provides excellent survivability and maximal multiple-hit capability, comparable to NxRA.
It is an object of the present invention to provide a non-explosive energetic material suitable for NxRA which does not contain explosive material and fulfills its protective function (high efficiency and high survivability of the armor), whilst the non-explosive energetic material lowers the requirements of transportation and logistics according to various standards e.g. UN regulations as appearing in the Recommendations on the Transport of Dangerous Goods.
It is a further object of the present invention to provide an armor element fitted for such an energetic material and where the armor is of comparable efficiency to SLERA and of comparable survivability to NERA.